Abstract:
We plan to acquire low-resolution spectra at mid-infrared wavelengths of
Orion Nebula protoplanetary disk systems using a highly sensitive
spectrograph at the Gemini Observatory. Our goal is to determine the grain
properties of proto-planetary disks associated with stars having ages <2 Myr.
The proposed observations include sampling the emission from proto-planetary
disks that
we suspect harbor disks with relatively larger grains than the disks very
near the Trapezium that we have previously studied at mid-infrared
wavelengths. Observed differences in the grain properties will enable us to
investigate early critical phases in the development of these disks. To
determine the grain properties, low resolution mid-infrared spectra will be
used to detect the Si-O stretch band of silicates at 9.7 microns, which may
be modeled to determine basic characteristics of the silicate grains
including shape, typical size, and crystallinity. These observations will
enable us to constrain current grain and disk models for photo-evaporating
disks at a range of radii from an external UV source and further our
investigations of proto-planetary disks in Orion.